The development of the mammalian gustatory sense will be investigated to determine the time of onset of function and to describe any changes in taste function as the sensory system develops. The influence of intrauterine taste experience on the establishment of adult taste sensitivities and preferences will also be studied. Fetal, newborn, and adult sheep will be used in physiological and behavioral experiments. The taste receptors of the fetal lamb are functional for a least the last third of gestation and may begin to function earlier. To establish when the peripheral taste system begins to function, electrophysiological recordings will be made of neural responses from the primary taste afferents from the time of taste bud appearance throughout morphological development. Neurophysiological taste responses recorded in the fetus will be compared to those in newborn lambs and adult sheep. The extent to which the fetus can actually perceive the taste of its liquid environment, the amniotic fluid, will be assessed. As a measure of perception, the swallowing activity of the fetus will be continuously monitored using an electromagnetic flow transducer implanted in the fetal esophagus. Attempts will then be made to modify normal swallowing behavior by injecting taste stimuli into the amniotic fluid. The role which early taste experience may play in establishing the gustatory sensitivity and preferences of the newborn lamb and adult will be investigated. An attempt will be made to establish a novel taste preference in the newborn by prolonged intrauterine exposure of the fetus to a specific taste stimulus. These experiments will detail the functional development of the sense of taste and will elucidate the possible biological significance of the gustatory sense during intrauterine life.